Abangkis - INTO KOTLIN A PRAGMATIC WAY

Transcript

1. INTO KOTLIN: A PRAGMATIC WAY
2. HELLO! I am Abangkis Pribadi I am 2 months android developer. You can find me at @abangkis 2
3. About Kotlin ▸ Kotlin is a statically typed programming language that runs on the Java virtual machine ▸ Can also be compiled to other language such as javascript, android & native ▸ Publicly Unveiled July 2011 after 1 year of development ▸ Relaxes Java’s restrictions, allow functional programming style
4. Great things about kotlin ▸ Concise Drastically reduce the amount of boilerplate code ▸ Safe Avoid entire classes of errors such as null pointer exceptions ▸ Interoperable Leverage existing libraries for the JVM and the browser. Can work with existing java code in Android ▸ Introduce new approach Coroutines, Ktor architecture
5. Things to consider when migrating ▸ The language itself ▸ The ecosystem (library, framework, doc, googleable/stackoverflow) ▸ Your team ▸ Your code, your utility class & lib ▸ How long do we need to be back to the same productivity, and more! (how long must we take a hit on productivity)
6. Why Now? - Timeline ▸ July 2011 - Publicly Unveiled (after 1 year of development) ▸ February 15, 2016 - Kotlin v1.0 was released ▸ Google I/O 2017 - Google announced first-class support for Kotlin on Android (wizzard, kotlinx.android.synthetic, gradle, etc) ▸ September 14, 2018 - Koin 1.0.0 unleashed ▸ October 29, 2018 - Kotlin coroutine 1.0 released ▸ November 19, 2018 - Ktor 1.0 released
7. Why Now? - Talks
8. Why Now? - Development Speed ▸ Less code ▹ kotlinx.android.synthetics ▹ Set listener / anonymous class ▹ Data class ▹ At least 20% less code vs Java ▸ Tools ▹ More tools are built for kotlin ▹ Popular library now support kotlin ▸ New Arsenal ▹ Kotlin coroutine
9. 1. Learning Kotlin Let’s Do It. Let’s Learn Kotlin
10. Learning new stuff - the long way ▸ Concept ▸ Syntax ▸ Gotchas ▸ Common & Best practices
11. “ Prag·mat·ic /praɡˈmadik/ Adjective dealing with things sensibly and realistically in a way that is based on practical rather than theoretical considerations.
12. Learning new stuff - pragmatic way ▸ Concept - Minimum ▸ Syntax - Minimum ▸ Gotchas - Immediate ▸ Common & Best practices - Immediate The goals is to learn the essential to make it work. Supplement it with our experience. While adding new knowledge over time.
13. 2. Pragmatic Kotlin for Android Let’s learn new stuff, new way 13
14. Beware ▸ Leveraging old knowledge ▹ Java & Best practice knowledge ▹ Android dev knowledge ▹ Written blog ▹ Reads articles about kotlin
15. Start from Zero ▸ The things that we know ▹ Interoperability with java ▹ Can be used parallel with java in android project ▹ Have simpler syntax ▹ Can mix between OOP and Functional Programming ▹ Design specially to handle null safety ▸ IDE Support ▹ Java to Kotlin converter ▹ Kotlin bytecode decompiler
16. Basic ▸ val vs var ▹ var is mutable variable. You can change the variable later on ▹ val is immutable variable. You can’t change the variable but you can still manipulate the content ▸ Null Safety ▹ Kotlin's type system is aimed at eliminating the danger of null references from code ▹ Type system distinguishes between references that can hold null (nullable references) and those that can not (non-null references) ▹ The goals is to make your code cleaner and safe from Null cases
17. New Syntax ▸ If you’re used to java, need time to accustomed to this type of syntax (even some of you would protest a lot) ▹ Reverse notation ▹ Infer type ▹ The curly braces (Scope) ▹ Etc ▸ Take it slowly, you’ll get used to it
18. The Functional Side ▸ In Kotlin function is the first class citizen. ▹ That means that they can be stored in variables and data structures, passed as arguments to and returned from other higher-order functions. You can operate with functions in any way that is possible for other non-function values. ▸ That means we work a lot with anonymous function/ Lambda expression ▹ Lambda expressions are 'function literals', i.e. functions that are not declared, but passed immediately as an expression val sum = { x: Int, y: Int -> x + y }
19. Evolve your code ▸ Android Synthetics ▸ OnClickListener ▸ Recyclerview ▹ Create Kotlin Adapter ▹ Convert Item to kotlin item data class ▹ Populate with mutable list of ▹ Simplify the adapter ▹ Add on item click
20. 2. Infrastructure Let’s take a look at the rest 20
21. Infrastructure ▸ Architecture component ▹ Lifecycle-aware components ▹ LiveData ▹ ViewModel ▹ Room ▸ Dependency Injection ▸ Repository Pattern ▸ Retrofit
22. Dagger Dagger vs Koin Koin 22
23. Using Koin ▸ Create the repository ▸ Create the module ▸ Extend the application, startKoin ▸ Create view model ▸ Access it from activity
24. Room Database ▸ Entities, Dao’s works the same ▸ Even simpler with kotlin format and Koin Injection ▸ All we have to do is to wire it up to koin
25. THANKS! Any questions? You can find me at @abangkis & medium.com/@abangkis Source available at https://github.com/abangkis/IntoKotlin/ 25
26. CREDITS Special thanks to all the people who made and released these awesome resources for free: ▸ Presentation template by SlidesCarnival ▸ Photographs by Death to the Stock Photo (license) 26